Formation of indophenol, indaniline, indamine, azomethine, phenoxazine, phenazine and like dyes by reaction of the oxidation product of an aromatic primary amine color developing agent formed by oxidation with an oxidizing agent of exposed silver halide and a coupler to provide color dyes is well known in color photography. In a photographic system of this kind, the subtractive color process is employed in which color images are formed from yellow, magenta and cyan dyes.
Of them, phenol or naphthol couplers are generally used for forming cyan color images. However, since the couplers have an unfavorable absorption in the green color range, severe problems in terms of a noticeable reduction in color reproducibility occur. Therefore, the solution of the problem is desired.
Recently, various cyan couplers of heterocyclic compounds have been proposed, in addition to phenol and naphthol couplers. Above all, imidazotriazole couplers as described in Research Disclosure, No. 16216 (1977) are typical examples. ##STR2## However, the dyes formed from the couplers described therein have a wavelength range of from 576 to 612 nm, and the wavelength is short. Further, these dyes have a broad half-value width.